Abstract: Root microbes strains isolated from winter wheat root were used i n experiments with different media and growing conditions. The results indicated that:1) There was no significant difference between cultivations vermiculite+soil+(NH₄)2HPO₄+urea medium and field condition, while the data got under vermiculite only were quite different from that in the field.2) Roo t microbes had distinct promoting effects on some yield related characters such as root length, root dry weight, root activities, the number of tiller and effectiv e ears . However, microbe effects were subtle on weight per thousand grains and grains per ear.3) An effective strain, Streptomyces sp. St56, was selected. Under field conditions, the strain increased the root length, root dry weight, root activities, number of tiller, number of effective ears and yield by 11.33%, 15.37%, 18.52%, 19.37%, 12.28% and 15.64% respectively.

Key words: Winter wheat, Root microbes, Root development, Yield relate d characters